Not silly at all. put any extra money into a savings account until you have enough to pay it off in full. the extra free income a month is a lot and is well worth paying it off early.
What extra free income? If you spend money on paying off your loan you are having a lower income. If you're saying after you have paid it off, then using the money you used to pay off your loan in the first place and the use of high interest accounts you will be better off.
Think of someone who lives 3 years in a world of zero inflation.
In year 1 they start off with 10k of debt with interest rate of 3%.
Each year they earn 25k paying 20% to pay for the loan.
in the first year they pay 5k and they reduce the loan from (10,000 x 1.03) to 5,300. He has 20k to consume that year. He could if he wanted pay off the 5,300 and consume only 14.7k. He then earns 25k the following years.
So he consumes 14.7k , 25k , 25k.
But he could have saved that 5,300 in a 4% (after tax) savings account.
So at the end of year 1 he consumes 14.7k, has debt of 5,300, and savings of 5,300.
In year 2 he again is forced to pay 5k reducing his loan from (5300 x 1.03) to 459. His savings increase to (5300 x 1.04 = 5512). In this year (just to equate to the example where he pays the loan off) he gets 20k from income withdraws 5k of his savings.
So in year 2 he consumes 25k, has debt of 459 and savings of 512.
In year 3 he pays the rest of his debt of (459 x 1.03 = 473). So in year 3 he consumes 25k - 473 + (512 x 1.04) = 25,059.
Therefore, where he doesnt pay off his loan as quickly as possible, his consumption is
14.7k, 25k and 25,059.
Strictly better than before.
This can be extended to someone living for x number of years (doesnt have to be years, could months, weeks or even days, but years makes interest calculations easier). This also uses a 1% difference between loan interest and savings interest, but with ISAs this can be a lot larger.